A document search system may index millions of documents associated with a corpus. The index for the search system may be an inverted index that may include posting lists. Some posting lists may represent a term and documents that contain the term. Other posting lists may represent a property and documents that have the property. The search system may also include other information, such as metadata for the posting lists and documents and/or parsed and encoded document content. In a distributed environment, the index may be divided among various machines by document, by term, or both. Every day the documents of the corpus may change, and often a document, such as a news organization's home page or a blog, may change several times a day. Some search systems may apply updates to documents in a near-instant manner to keep the index as fresh as possible. However, some of these updates may include bad data that can cause the search system to crash. But in a system that supports instant or near-instant updates, there may not be time to test for such bad data in an update. This may lead to index unavailability.